1. Field
Embodiments of the invention relate to mapping source and target objects.
2. Description of the Related Art
Some conventional systems enable a user to map columns of one table to columns of another table (i.e., to form mappings between columns). A mapping may be described as a relationship between two objects. A mapping may be represented by a mapping line. A mapping line may be formed by one or more segments and may include a hub (e.g., a square drawn on a mapping line). It is possible for there to be a large number of mappings (e.g., in the hundreds) of columns. The mappings may be shown on a display screen of a computer monitor, for example, by illustrating the tables and their columns and drawing lines between mapped columns.
It is difficult to comprehend schema mappings when the mapping lines connecting objects are not straight. In some contexts, the mapping lines have hubs. A user may select a hub to select a mapping line (i.e., because it may be difficult to select a particular line when many are displayed) or to obtain information about a mapping line. In many systems, hubs are drawn so that they do not overlap each other. In this situation, conflicts may arise such that the mapping lines are not always drawn as straight lines between source and target objects.
Thus, when the mapping lines are drawn without regard to the relative positions of the source and target nodes, a few outlying mapping lines may interfere with the drawing of a sequence of parallel mapping lines, making the mapping display harder to comprehend.
FIG. 1 illustrates prior art mappings for which mapping lines are drawn in order from top to bottom on a source side. FIG. 1 illustrates a main view 100 that displays an overview in accordance with certain embodiments. The main view 100 includes three areas: a source area 110, a mapping area 120, and a target area 130. The source area 110 shows source schemas, while the target area 130 shows target schemas. The mapping area 120 shows mapping lines that include hubs (e.g., mapping line 122 with hub 124). In this example, the source and target schemas are positioned so that source table EMPLOYEE 112 is lined up with target table EMPLOYEE 132. The columns of tables 112, 132 are mapped (shown with mapping lines) in order from top to bottom according to the columns of the source table 112 (i.e., from FNAME, MINIT, . . . DNO), but some of the mapping lines are not straight because the outlying mapping lines between source table DEPT_LOCATIONS 114 and target table DEPARTMENT 134 have been drawn first, and the source table EMPLOYEE 112 to target table EMPLOYEE 132 mapping lines that would have been drawn in the space that the mapping lines for tables 114, 134 occupy are then drawn below them. This is done to avoid having hubs overlap.
FIG. 2 illustrates prior art scrolled mappings for which mapping lines are drawn in order from top to bottom on a source side. In FIG. 2, the main view 100 (FIG. 1) is illustrated, but with the source area 110 scrolled up a little. The outlying mapping lines for tables 114, 134 once again prevent the mappings from the source table EMPLOYEE 112 to the target table EMPLOYEE 132 to be drawn as straight lines.
Thus, there is a need in the art for improved mapping of source and target objects.